This invention relates to a scroll fluid machine serving as a gas compressor for raising pressure of refrigerant gas or the like, a gas expander or a liquid pump and, more particularly, to a structure for feeding oil to each bearing and each sliding surface of the scroll fluid machine.
A hermetic scroll compressor, which is an example of a scroll fluid machine, is known from U.S. Pat. No. 4,551,082. The scroll compressor comprises a closed housing and a compressor component arranged in an upper portion of the closed housing. A feed oil structure of the scroll compressor includes an oil reservoir defined at a bottom of the housing. A crankshaft has its lower end which is submerged in the oil within the oil reservoir. The crankshaft is formed therein with a feed oil passage communicating a lower end face of the crankshaft with various bearing sections. Centrifugal force or pressure difference is utilized to feed the oil within the oil reservoir to the bearing sections through the feed oil passage.
The feed oil structure disclosed in the abovementioned U.S. Pat. No. 4,551,082 is applicable to an arrangement in which a compressor component is disposed in an upper portion of a closed housing, but is not applicable to an arrangement in which the compressor component is disposed in a lower portion of the housing or an arrangement in which a crankshaft for driving the compressor component is arranged to have an axis extending horizontally.
Another feed oil structure is known from U.S. Pat. No. 4,538,975, in which oil contained in suction refrigerant gas is separated from the latter and the separated oil is fed to various bearing sections. It is difficult for such feed oil structure, however, to secure a sufficient amount of oil.